Condensed Consolidated Statements of Changes in Equity and Income (unaudited) - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	Select Medical Corporation	Common Stock	Common Stock Select Medical Corporation	Capital in Excess of Par	Capital in Excess of Par Select Medical Corporation	Retained Earnings (Accumulated Deficit)	Retained Earnings (Accumulated Deficit) Select Medical Corporation	Total Stockholders’ Equity	Total Stockholders’ Equity Select Medical Corporation	Non-controlling Interests	Non-controlling Interests Select Medical Corporation
Balance at Dec. 31, 2017	$ 640,818	$ 640,818
Redeemable Non-controlling Interests
Net income attributable to non-controlling interests	25,896	25,896
Issuance and exchange of non-controlling interests	163,659	163,659
Distributions to and purchases of non-controlling interests	(215,847)	(215,847)
Redemption adjustment on non-controlling interests	164,065	164,065
Other	983	983
Balance at Sep. 30, 2018	$ 779,574	$ 779,574
Balance (in shares) at Dec. 31, 2017	134,114,715	100	134,115,000	0
Balance at Dec. 31, 2017	$ 932,604	$ 932,604	$ 134	$ 0	$ 463,499	$ 947,370	$ 359,735	$ (124,002)	$ 823,368	$ 823,368	$ 109,236	$ 109,236
Increase (Decrease) in Stockholders' Equity
Net income	113,167	113,167					113,167	113,167	113,167	113,167
Net income attributable to non-controlling interests	8,157	8,157									8,157	8,157
Issuance of restricted stock (in shares)			1,222,000
Issuance of restricted stock	0		$ 1		(1)
Forfeitures of unvested restricted stock (in shares)			(88,000)
Forfeitures of unvested restricted stock	0		$ 0		0
Vesting of restricted stock	15,059				15,059				15,059
Repurchase of common shares (in shares)			(285,000)
Repurchase of common shares	(5,640)		$ 0		(2,989)		(2,651)		(5,640)
Exercise of stock options (in shares)			176,000
Exercise of stock options	1,633		$ 0		1,633				1,633
Additional investment by Holdings		1,633				1,633				1,633
Dividends declared and paid to Holdings		(5,640)						(5,640)		(5,640)
Contribution related to restricted stock award issuances by Holdings		15,059				15,059				15,059
Issuance and exchange of non-controlling interests	77,815	77,815			1,553	1,553	74,341	74,341	75,894	75,894	1,921	1,921
Distributions to and purchases of non-controlling interests	(92,020)	(92,020)			(932)	(932)	(83,617)	(83,617)	(84,549)	(84,549)	(7,471)	(7,471)
Redemption adjustment on non-controlling interests	(164,065)	(164,065)					(164,065)	(164,065)	(164,065)	(164,065)
Other	$ 858	$ 858					(275)	(275)	(275)	(275)	1,133	1,133
Balance (in shares) at Sep. 30, 2018	135,140,269	100	135,140,000	0
Balance at Sep. 30, 2018	$ 887,568	$ 887,568	$ 135	$ 0	$ 477,822	$ 964,683	$ 296,635	$ (190,091)	$ 774,592	$ 774,592	$ 112,976	$ 112,976